IDAHO SPRINGS, Colo. (CBS4) – Since Memorial Day weekend a new zipline has run along Interstate 70 west of Idaho Springs, and officials with the Colorado Department of Transportation say drivers are slowing down to watch.

They say that’s a problem on a stretch of the interstate in the mountains where summer traffic is already a major issue.

After receiving several complaints about cars slowing down, CDOT officials did a study focusing the traffic from Georgetown to Idaho Springs. They compared traffic patterns last year and compared them to the period of time since the zipline has been in operation. On some days, the traffic from Georgetown to Idaho Springs in both directions was 5 mph slower and 11 minutes longer.

Jeff Hale with Colorado Adventure Center, which operates the zipline, says he’s seen drivers slow down and wave but he says his business is not responsible for added traffic.

“There’s always been traffic on Interstate 70,” Hale said. “The Department of Transportation had a gentleman come by saying he was looking at the differences in traffic patterns and we were reluctant to believe that we are a part of that.”

The “Clear Creek Zip Trip” ride is one of many zipline experiences across the state. It involves five wooden towers and ziplines that cross the river and reach higher than 65 feet above the ground. Operators plan to remain in operation this year until weather no longer makes that possible.

CDOT spokeswoman Stacey Stegman told CBS4 I-70 traffic is certainly a major issue, but that in this case their hands are tied.

“It’s not like we can just drape the highway,” CDOT spokeswoman Stacey Stegman told CBS4. “We can’t put messages on a sign that say, ‘Don’t watch the zipliners.’ ”

Stegman said CDOT supports economic growth along I-70, but when it comes to the zipline it’s hard to balance business with the traffic issues.

“Traffic sees people on the ziplines over the highway, and we believe it’s starting to slow traffic a little bit,” she said.

John Cantamessa, the owner of the zipline, told CBS4 by phone that the traffic problem is not caused by the zipline, but instead “CDOT burying its head in the sand for the past 20 years.”

Hale said he hopes travelers will continue to drive safely along Interstate 70.

“We hope they drive safely arrive safely and when they’re ready to have fun come back and see us,” he said.